Fill Rate
The percentage of ad requests that were successfully answered with a displayed advertisement.
Fill Rate is a key performance indicator for publishers that measures the efficiency of their ad inventory. It represents the ratio of delivered ads to the total number of requests sent to ad servers.
Why Fill Rate matters
An ideal fill rate is 100%, meaning every opportunity to show an ad was filled. A low fill rate indicates “wasted” inventory where an ad could have been shown but wasn’t, resulting in lost revenue.
How to calculate Fill Rate
The formula for Fill Rate is:
(Total Ads Delivered / Total Ad Requests) * 100
For instance, if your website made 10,000 ad requests but only delivered 8,500 ads, your fill rate would be 85%.
Reasons for a low Fill Rate
- Lack of advertiser demand: No advertisers are currently bidding for your specific audience or niche.
- Technical issues: Slow page load times or configuration errors preventing ads from loading.
- Ad blockers: Users utilizing software that prevents ad requests from being completed.
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Related Terms
Ad Inventory
The total amount of space available on a website or app for advertisements to be shown.
Click-Through Rate
The percentage of users who clicked on a specific link or advertisement compared to the total number of users who viewed it.
Effective Cost Per Mille
The estimated earnings a publisher receives for every 1,000 ad impressions served, accounting for all types of revenue.
Programmatic Advertising
The automated buying and selling of online advertising space in real-time.